1. Field of the Invention
The present invention relates to method and equipment for preparing specimens observed with a transmission electron microscope or other instrument.
2. Description of Related Art
The following methods A)-C) have been heretofore known to prepare thin-film specimens observed with a transmission electron microscope (TEM). These methods A)-C) are described below with reference to the drawings.
A) Thinning of a Bulk Specimen (see FIGS. 1A to 1E)
A bulk specimen may be thinned by a procedure consisting of the following steps 1)-5):
1) The specimen is cut to a thickness of about 1 mm and polished. Then, the specimen is roughly polished to a thickness of about 100 μm (FIG. 1A).
2) The specimen is blanked to a diameter of 3 mm (FIG. 1B).
3) One surface of the specimen is mirror polished flat (FIG. 1C).
4) The roughly polished surface of the specimen on the opposite side of the mirror-polished surface is dimpled with a dimple grinder. The center of the formed dimple is formed as a mirror surface having a thickness of about 10 μm (FIG. 1D).
5) The specimen is set in ion milling equipment. Argon ions are directed at the specimen from both sides while rotating the specimen continuously to thin it (FIG. 1E).
B) Preparation of a Section of a Specimen (see FIGS. 2A to 2G)
A section of a specimen, such as a silicon wafer on which an integrated circuit has been formed, is prepared by the procedure consisting of the following steps 1)-7).
1) Plural specimen materials, each 5 to 10 mm square, are cut from a silicon wafer. The specimen materials are bonded together with epoxy resin to form a specimen (FIG. 2A).
2) A cylinder having a diameter of 2.3 mm is blanked out of the specimen by an ultrasonic machine (FIG. 2B).
3) The extracted piece of the specimen having a diameter of 2.3 mm is buried in a metallic pipe having an outside diameter of 3 mm and an inside diameter of 2.3 mm together with epoxy resin (FIG. 2C).
4) The piece of the specimen buried in the metallic pipe is sliced to a thickness of about 1.0 mm by a cutter (FIG. 2D).
5) One surface of the piece of the specimen is mirror polished (FIG. 2E). shielding material to etch the irradiated surface portions around the non-irradiated surface portion while leaving the non-irradiated portion unetched. This method is characterized in that the ion beam is directed at the shielding material and the specimen material from different directions and that the directions of irradiation of the ion beam are so set as to form a thin-film specimen becoming thinner in going downwardly from the non-irradiated surface portion.
Accordingly, in the present invention, a specimen preparation method and a specimen preparation equipment are offered which permit one to easily prepare good thin-film specimens adapted for observation.
Other objects and features of the invention will appear in the course of the description thereof, which follows.